The interior noise level of an automotive vehicle passenger compartment plays a major role in a customer's perception of overall vehicle quality. Interior noise level therefore has become a major consideration in the design, construction, and assembly of the vehicle body structure, including design of the vehicle door sealing system.
The noise sources generated in the proximity of the exterior body surface, which eventually propagate through various transmission paths into the passenger compartment, have several components: aerodynamically generated noise, termed "wind noise"; noise generated by the tire rolling over the road surface; and noise from the engine and exhaust system. Wind noise is generated mainly on the side glass windows of the doors by the turbulent flow of air around the "A" pillar structures and other recesses and projections in the body surface, such as the outside mirrors and drip rails and is transmitted into the vehicle interior through body panels, side window glass, and the seal gap between the door and DOP (Door Opening Panel). To keep wind noise out of the passenger compartment, a door weatherstrip seal system, perhaps having several layers of sealing bulbs, is typically placed in the seal gap.
Usually, automotive door seals are designed using the "bread board" and other "build and test" procedures. The bread board is a five (5) times oversized representation of the rubber seal cross-section and the sealing surfaces. It consists of two components: a stationary component sculptured out of wood to represent the DOP sheet metal; and, a moveable component to which is attached an oversized rubber seal cross-section. By moving the movable board piece, it is possible to see the seal deformed shape and its contact with the sheet metal when the door is closed. If there is not enough contact area to prevent water leakage, or if an undesirable compressed seal shape is attained, seal design engineers must go back to their drawing board and develop a new design ("build and test" procedure). Since the "bread board" procedure only gives door sealing response locally, vehicle seal designers do not know whether their seal design meets door closing effort, water leakage, and wind noise targets before actually manufacturing the door seal system and testing it on the vehicle. In addition, this procedure is time consuming and expensive.